Stoker furnace



July 25, 1939. E. B. PRiEBE STOKER FURNACE 2 Sheets-Sheet 1 Filed June26, 1936 ATTORNEYS E. B. PRIEBE STOKER FURNACE July 25, 1939.

Filed June 26, 1936 2 Sheets-Sheet 2 m mm m Yw NP m M m m M T a w. vvm r5 W Patented July 25, 1939 UNITED STATES PATENT OFFICE 11 Claims.

This invention relates to stoker furnaces,.especially boiler furnaceswith progressive feed, such as underfeed, overfeed or chain grate; the

fuel bed advancing towards and upon a discharge I plate or member overwhich the refuse discharges into an ash pit. In one form of such boilerfurnace there is a water cooled rear or bridge wall,- which wall, or thefront or fire side of which wall, is located above the discharge plateand which wall terminates above the discharge plate, thereby forming anash discharge gate or throat through which the bed of refuse is thrust'or travels 'rearwardly in discharging to the ash pit. The reference toa rear wall is intended to desig nate the furnace wall adjacent thestoker discharge end; in the case of usual stokers it may be the bridgewall, generally exemplified by Priebe and Miner Patent No. 1,633,418 ofJune 21, 1927, but in the case of so-called Type E stokers it may be-theequivalent side wall, at each of the two sides, constituting in effecttwo rear walls, and exemplified by Priebe and Miner Patent No. 1,333,952

of December 1, 1931, a division of 1,633,418.

The general object hereof is to improve the efficiency and life of thedischarge structure involving the stoker discharge plate and the bridgeor equivalent wall above the ash pit. A particular object is to affordeffective water cooling of the discharge throat not merely as to thebridge wall front side, but the arch formed beneath it above the plateand pit. A further object is to afford an improved system of coolingtubes for the lower part of a bridge wall and protecting blocksshielding the same from the heat of the fuel bed.

Further objects and advantages will be explained in the hereinafterfollowing description of an illustrative embodiment of the invention.

In the accompanying drawings Fig. 1 is an interior elevation of a stokerfurnace embodying the present invention, seen in right hand view; theright hand side of this figure being considered the rear side of thefurnace, and the view. being taken partly in vertical fore-and-aftsection.

Fig. 2 is a front elevation of the lower part of the rear or bridge wallof Fig. 1.

- Fig. 3 on a larger scale and in front elevation shows a portion of thelower part of the wall, with the covering blocks omitted from some ofthe water tubes.

Fig. 4 on the same scale with Fig. 3 is a right elevation and sectiontaken on the line 4-4 of Fig.

Fig. 5 is a partial right elevation and section view corresponding inpart with 1 but show- 5 ing a modified structure.

In Fig. 1 is shown a boiler furnace containing a progressive feed stokerof conventional type, including for example an underfeed retort stoker10 along which the fuel bed is advanced toward the rear, as byreciprocating pushers in the re- 6 torts, and beyond the main stoker l0an extension grate H comprising for example reciprocating grate memberswhich receive the fuel bed by overfeed from the main stoker and continueits travel to the discharge.

The furnace chamber above the stoker or grate is bounded at the front bya wall l2 and-by opposite side walls I3. There is shown, beyond thestoker or grate, a side wall twyer l4 extending substantially higherthan theretorts of the stoker. The line l5 may indicate approximatelythe fuel bed'outline.

At the end of the fuel bed travel the stoker or grate delivers therefuse or ash over a discharge plate or dump member l6, shown ofconventional 20 construction. This dump plate is preferably a fixedmember, but is mounted upon a shaft I! by which it can be adjusted so asto change the height of the discharge edge of the plate.

The edge of the discharge plate I6 extends 25 over, and discharges into,an ash pit l9 comprised between front and rear walls 20 and. 2|, the pitbeing closed at the ends and having at its foot any suitable means forprogressive or intermittent removal of ashes. I 30 The furnace hereof ispreferably, a boiler furnace, and the boiler may be of any type ordesign. Conventionally it is shown as comprising a low header or drum23, an upper rear header or drum 24 and an upper front header or drum 3525. Extending between the drums 23 and 24 is a system of boiler tubes26, partly indicated, and between the drums 24 and25 are tubes 21, steambeing drawn from one of the upper drums as usual. 40

In front of the second or'downflow pass 29 of the boiler is the rear orbridge wall of the combustion chamber, over which the products ofcombustion travel into the second pass. This upwardly extending orbridge wall may be composed 45 of several cooperating portions. Thus onthe foremost series of tubes 26 isshown a system of refractory blocks 30forming with these tubes a closed wall. Below this closed wall portion30 is shown a closed refractory wall 3| which extends 50 downwardly andis then turned or curved rearwardly at 32, terminating adjacent to thepit wall '21 and drum 28.

The bridge or rear wall thus defined is shown as cooled by a system ofuptake water tubes 34 extending in cooling relation to or in front ofthe bridge wall, and eifectively forming a part of it. These uptaketubes 34 at their lower ends are extended substantially horizontally astubes 35 connecting-with a header, as the drum 2], exterior to the ashpit. These tubes, after coming forward from the header 23 through theash pit wall, or between'it and the bridge wall, extend substantiallyhorizontally above the ash pit, extracting heat from the ash therein,and thence curve upwardly into the uptake tube portions 34 which, nearthe top of the bridge wall, are curved into slanting extensions leadingtoan upper header or drum, as the upper boiler drum The lower part ofthetube system 34, where exposed to the hottest part ofthe flre, is coveredwby a system of protecting blocks 31. These are preferably cast ironblocks, either fused or cast directly upon the tubes or else coupled orbolted the eon, but they may be composed of silicon carbide or otherheat conducting refractory material. These blocks or coverings 31 arepreferably applied in short sections, as usual, spaced for example onequarter inch, thus to allow for expansion or growth and prevent warpingof the,

' tubes.

This system of tube-protecting blocksfl is shown as extending downsubstantially to the bend of the tubes, but not necessarily continuedalong the horizontal tube portions 35 that are exposed merely to the ashpit. At thefoot of the series of protecting blocks 31 is shown a specialblock 38 or ",shaped with an angular corner or edge 40 and constitutinganose'or gate block, above or opposed to theplate l8 and therewithforming the refuse throat or gate. In Fig.

I 5 the nose blocks 38, or the transverse seriesgo" A convenientconstruction of nose block' thereof, are shown as applied directly uponthe uptake tubes 34. In Figs. 1 to 4 however the special nose block 3!,having the projecting corner 40, is shown mounted or attached upon aspecial transverse water tube ll extending across the width of thefurnace closely below the bend of. the tubes 34. While the special noseblock might be cast or fused upon the tubes as in Fig. 5 it ispreferably bolted on as shown in Figs. 1 to 4, being thus replaceablewhen burned away by the heatpf the fire.

mounting, as shown in Figs. 1 to 4 is as follows.

The block 39 is formed to hook under the transverse tube II, for exampleit may have a face portion and two legs which straddle the trans--versetube. The tube is thus thoroughly pro- At the back end ofthetected from the heat. leg or each leg of the block is shown anextension or bolt 42, and the legs or bolts may be con-: tinued betweenand beyond the system of uptake F tubes 34. By this arrangement a crossbar may be located back of the tubes 34, the bolts passing throughopenings in the cross bar, and nuts 44 at .the ends of the bolts servingto clamp together these various elements, the block, the transversetube, and the uptake tubes. As seen in Figs. 3 and 4 the blocks I! arenot merely shaped to straddle the transverse'tube 4|, but at cleaner.

is bent forwardly and then transversely, extending through a side wallIt and constituting the tube 4|. The far end of the tube 4i passesthrough the opposite side wall of the chamber where it has a coupling 41connecting it with an uptake or extension tube 48, shown as passing backthrough the wall and rising .vertically to the height of the bridgewall, thence extending at 48 to an upper header or drum, forexampie-slanting upwardly to the front-drum 25.

Referring further to Fig. 5 this shows, as do Figs. 1 to 4, a boilerfurnace having a stoker grate l0 whereon the bed I! of fuel and ashtravels progressively rearwardly toward a point of discharge into a rearash pit i9, and having a fixedposition spill-plate it over which. suchbed slidingly discharges substantially continuously; into such ash pit;and combined with such stoker grate and spill-plate, the bridge or 'rearwall iii-1| overhanging said spill-plate and comprising a system ofseparate uptake water tubes 34 in circulation with the boiler,eachextending continuously, first along the under part of the wallspaced above the spill-plate and thence bent curvedly around the lowerinner corner of said wall and thence extended upwardly along the innerside of the wall, for keeping cool the wall, and a system of high-heatconductive or metal blocks 31,-etc., covering such uptake water tubes atand near such wall corner,-such tubes being in. cooling relation to suchblocks; said spill-plate and said covering blocks at the wall comerbeing spaced so close together as to define between them an ashdischarge throat which is vertically narrow and of short length in' thedirection of discharge, through-which throat the bed must beconstricted, compressed or squeezed by its continuous forced travel,crowding it through toward'dischar'ge, and the bed must thus traversethe, short length ofthroat-in contact with both the spill-plate belowand corner blocks above whereby the bed effectively seals the throatcontinuously against undue air inflow, and said cornerblocks not onlythereby protecting the tubes against undue heat exposure, but alsodirectly.

taking and protecting the tubes against the thrust and abrasion of thetraveling bed, and at the same time affording a contact-cooling effectoperating to chill the top surface of theadvancing bed, thus congealingany molten material and preventing adhesion and facilitating passageafford an efllcient ash gate or throat serving the objects first abovestated. In en'ect'the tubes and blocks constitutes cooled arch or topwall to the discharge gate and to the ash pit. @ach of the tubes Itmaybe a' single bent tube ex tending from header 2! toheader 2i, andthus is well able to be cleaned by driving through it at suitableperiods the usual kind of boiler tube The described arrangement ofabridge wall extended above the discharge plate and ash pit admits ofthe provision of an observation door or window, "and such a door 53 isindicated in Figfi5. By observation through the door If the discharge ofrefusethrough the gate may be observed, and the discharge plate It maybe vertically adjusted to proper position during such ing of the noseblock will cause pressure between the nose block and tube ll forintimate contact and heat conduction.

An advantageous bridge wall construction is that shown, wherein thelower part of its inner side is closed between the tubes 34, as at 3|,the tubes here having the face protecting blocks 31, whereas higher up,where the heat is less intense, the structure changes, the tubes herebeing free and surrounded by the hot gases, the closing of the wallbeing slightly outwards of the tubes, as at 30; so that in effect theupper parts of tubes 34 constitute a screen, the gases passing betweenthe tubes on their way from the combustion chamber and main pass to thetop of the second pass 29 of the boiler.

I claim:

1. In a stoker furnace a discharge plate over which the stokerrearwardly discharges, a rear or bridge wall spaced above the plate toform therewith a throat discharging rearwardly to an ash pit, a systemof water tubes in circulation with the boiler extended in coolingrelation to the under side of said wall above the ash pit and throatandthence as uptakes in cooling relation to the front side of said wall,and a horizontal water tube in circulation with the boiler and extendedtransversely along the under side of said wall for transversecirculation above such throat.

2. In a stoker boiler furnace a discharge plate over which the stokerrearwardly-discharges, a rear or bridge wall spaced above the plate toform therewith a throat discharging rearwardly to an ash pit, a systemof water tubes in circulation with the boiler extended as uptakes incooling relation to said wall, and a transverse tube below such uptakescarrying protecting blocks constituting the upper edge of such throat.

3. A furnace as in claim 2 and wherein the blocks protecting thetransverse tube protect also the uptakes and the uptakes carryadditional protecting blocks thereabove.

blocks engage both the transverse and uptake tubes and have meanssecuring them in position.

s. In a stoker boiler furnace a discharge plate over which the stokerrearwardly discharges, a rear or bridge wall'spaced above the plate toform therewith a throat discharging rearwardly to an ash pit, a systemof water tubes in circulation with the, boiler extended under said walland as uptakes in cooling relatiori'to said wall, a transverse watertube below such uptakes in circulation with the boiler, and a series ofblocks constituting the upper edge of such throat, detachably mountedin, protecting relation to the under side of said transverse tube.

7. A furnace as in claim 6 and wherein the blocks are shaped to straddlethe transverse tube and have couplings extended between the uptake Itubes and means there securing them.

8. A furnace as in claim 6 and wherein each throat block is shaped tohook over and protect the transverse tube with an extension back betweentwo uptake tubes.

9. In a stoker boiler furnace a stoker grate, and to the rear thereof adischarge plate over which the stoker rearwardly discharges and spillsinto an ash pit, a furnace rear wall above said plate, a system ofuptake tubes in circulation with the boiler and in cooling relation tothe under and front part of said rear wall, said plate and wall spacedapart and forming between them an ash discharging throat, and a seriesof throat-defining blocks in protecting relation to said tubes andforming the ceiling of such throat while said stationary plate forms thefloor thereof; and said rear wall comprising also a horizontal watertube in circulation with the boiler, ar-

ranged for transverse flow in protected relation to said protectingblocks.

10. In aboiler furnace having. a stoker grate whereon the bed of fueland ashtravels progressively toward a point, of discharge into an ash Icorner of said wall and thence extended upward-' 1y along the inner sideof the wall, for keeping cool the wall, and a system of high-heat-conductive blocks covering such uptake water tubes at and near such wallcorner, such tubes being in cooling relation to such blocks; saidspill-plate and said covering blocks at the wall corner being spaced soclose together as to define between them an ash discharge throat whichis vertically narrow and of short length in the direction of discharge,through which throat the bed must be constricted and crowded by itscontinuous forced travel toward discharge and must thus traverse theshort length of'throat in contact with both the spill-plate and cornerblocks whereby the bed effectively seals the throat continuously againstundue air inflow, and said corner blocks not only thereby protecting thetubes against undue heat exposure, but also directly taking the thrustand abrasion of the traveling bed, and at the same time affording acontactcooling effect to chill the top surface of the advancing bed thuspreventing adhesion and facilitating passage of the bed through suchthroat.

11. The combination as in claim 10 and wherein the stoker grate is of akind sloping downward toward the spill-plate at the rear, and the tubecovering blocks at and near the wall lower inner corner are metallicblocks intimately associated with the uptake water tubes, and saidblocks are shaped to present a saliently projecting nose which extendsacross the furnace and defines the upperrside of the throat and receivesthe thrust of the advancing bed.

ERNEST B. PRIEBE.

